Hi Canie. The main reason I prefer to use a tight cluster of quakes is that under some conditions their cause may not be the same. A good example is the following as there could be two causes for the swarm. This also applies to the swarms in the past near Tom’s Place just south Long Valley Calderas.

The Burney earthquake sequence is best described as an earthquake swarm. An earthquake swarm is a sequence with several earthquakes of comparable magnitude, which builds in intensity, rather than a mainshock-aftershock sequence with a single large earthquake followed by smaller aftershocks. Mainshock-aftershock sequences are typical of the large faults in California such as the San Andreas or Hayward. Earthquake swarms as well as mainshocks can occur in many parts of the state.

Volcanic eruptions or buried magma movement are generally preceded by earthquake swarms, but a swarm DOES NOT mean magma movement is occurring. Swarms associated with eruptions (such as Hawaii or Mt St. Helens) or buried magma movement (such as Long Valley) is very intense with hundreds of earthquakes lasting for days, months or years. The Burney earthquakes DID NOT occur in sufficient numbers to suggest an eruption or even magma movement is imminent. The earthquakes are not directly under a known volcano, but there are numerous volcanic centers to the southeast in the Hat Creek and Lassen volcanic fields. Generally, one must look for sustained seismicity and other observations as a harbinger of volcanic activity. As to the earthquakes cause, it seems premature to point to a volcanic processe. The swarm nature of the sequence and the geology of the region suggest the earthquakes may be in an area of weak crust.

This same kind of activity could also apply to the Coso Junction area. The curst is known to be on the thin side in that area and it is also a known volcanic area by evidence of the geothermal plant there. However other evidence was not present such as uplifting, tilting or the release or CO2 or Hydrogen sulfide. Then again this might be seen with the next swarm when it occurs. Just my thoughts. Take Care…Don in creepy town